Absolute dipole oscillator strengths for the photo-ionization and photoabsorption of COS (5-50 eV)

Absolute dipole oscillator strengths (cross-sections) for photoabsorption and photoionization (total and partial) of COS have been derived from electron energy loss and (e, 2e) coincidence measurements in the energy range 5-50 eV. The oscillator strength distribution of COS is concentrated at lower energies in comparison to that observed for the valence isoelectronic molecules CO₂ and N₂O, a result which reflects the atomic sulfur contribution to the total oscillator strength. Consideration of the total photoabsorption and photoionization cross-sections indicates that Rydberg levels populated by absorption in the 12-19 eV region can decay by competing neutral processes (dissociation, fluorescence) and autoionization. Strong autoionization is supported by the unusually large partial oscillator strength of the X²II(3π)^-1 channel in the 12-16eV excitation range. Finally, binding energy spectra recorded at excitation energies above 20 eV exhibit extensive final-state structure.The many-body character of these states and their total (summed) intensity variation with energy have been examined.